The present invention relates to a membrane keyboard panel.
A membrane keyboard has been developed which includes a plurality of laminate flexible polyester film sheets. Key pad labels are printed on a first sheet, and conductor electrodes are printed on a second sheet at positions corresponding to the key pad labels. Counter conductor electrodes are printed on a third sheet, and a spacer sheet is disposed between the second and third sheets. When a desired key pad label is depressed, the corresponding conductor electrode formed on the second sheet contacts the counter conductor electrode formed on the third sheet through an opening formed in the spacer sheet.
In such a membrane keyboard, it is desirable that a frequently used key is marked by a larger key pad label. Attention should be given to the difference of the pad size in order to ensure an accurate key input operation.
Accordingly, an object of the present invention is to provide a membrane keyboard which includes a larger key pad label and a smaller key pad label.
Another object of the present invention is to provide a membrane keyboard which ensures an accurate key input operation.
Other objects and further scope of applicability of the present invention will become apparent from the detailed description given hereinafter. It should be understood, however, that the detailed description and specific examples, while indicating preferred embodiments of the invention, are given by way of illustration only, since various changes and modifications within the spirit and scope of the invention will become apparent to those skilled in the art from this detailed description.
To achieve the above objects, pursuant to an embodiment of the present invention, a larger conductor electrode exactly corresponding to the larger key pad label is formed on the second sheet at the corresponding position. Furthermore, a larger counter conductor electrode is formed on the third sheet at the corresponding position, and the spacer sheet has an opening of the size corresponding to the larger key pad label. In a preferred form, the larger opening formed in the spacer sheet is divided into at least two sections, thereby uniforming the pressure required for conducting the key input operation of the respective key pad labels.